Help needed on XFRM! Thanks in advance.

Hi all,

I am working on a program to modify incoming packets by adding extra
headers to the IP packets. I heard that XFRM is the right approach for
this as IPSec use it to add authentication headers. However, I find
little documentations on this topic. I managed to find how to
manipulate the security association and the security policy through
the netlink interface. But I have no idea on how to add extra header.
Please help me if you have any clue. Thanks a lot!

BTW: If you have other method to achieve the same task, please let me
know as well. Thanks.

Regards,

Xia Yang